The present invention relates to a trolling device for allowing fishing from a boat at a desired water depth where fish are to be found.
Trolling devices are used in fishing to submerge a lure or other fishing device to a desired depth and to maintain it at that depth while the lure is pulled behind a moving boat. Some such devices comprise relatively heavy weights attached to the fishing line. Alternatively, so-called downrigger lines are used, which are suspended from the rear end of a boat and weighted down with heavy weights attached to their ends. One or more fishing lines are releasably attached at one or more depths along the length of the downrigger line, and the weighted line is lowered to the desired fishing depth carrying the fishing line or lines and attached lure with it. When a fish strikes a lure, the increased tension on the fishing line releases it from the downrigger line.
As an alternative to heavily weighted downrigger lines or fishing lines, trolling divers are sometimes used. Such divers are normally positioned along the length of the fishing line and include a planing surface at an angle to the horizontal, so that when they are pulled through the water they drag down or depress the lure. However, devices of this type generally are dependent on external conditions such as boat speed, water currents and the like which determine the final depth. Also, such trolling divers or platforms have a tendency to wobble from side to side as they are towed, or even to pop up to the surface under same conditions. Additionally, since these devices are connected in series with the fishing line itself, they can cause water resistance and difficulty in pulling in the line when a fish is caught.
U.S. Pat. No. 3,808,727 of Flanders describes a known trolling device or diver in which a plate has a variable, multiple position weight assembly attached to its front end as well as other adjustment mechanisms for controlling the angle of the plate and thus the distance of descent of the device. The device is secured to a tow line at its front end and to a lure at its rear end. Thus, the device is connected in series with the fishing line. In U.S. Pat. No. 4,581,842 of Kalberer, U.S. Pat. No. 4,129,956 of Neary and U.S. Pat. No. 3,898,759 of Jensen a trolling diver secured in series along a fishing line is designed to be re-orientated on a fish strike from a diving to a rising mode, allowing a caught fish to be played and reeled in more easily.
U.S. Pat. No. 4,212,127 of Daniels shows a different arrangement in which a fishing line is releasably secured to the diving plane, while the plane itself is slidably attached to a weighted downrigger line. This avoids the some of the problems of serially connected diving planes since the fishing line is detached from the diving device on a fish strike. However, it does require a heavily weighted downrigger line for operation.